Java:包装类文件

Question

我已经学习了Java软件包。不幸的是，我不明白为什么编译这些.java文件会导致编译错误。

我有以下3个Java文件：Node.java，InvertedFile.java和Postings.java，所有这些文件均在Mac OS X上的目录/Users/tracking/Desktop/implementation/mytree中。

package     mytree;
import      java.util.*;
// Node.java
public class Node 
{
    private int             label;          // unique integer identifier of this tree.
    private Node            parent; 
    private List<Integer>   leaves;         // the leaf value that this tree contains.
    private List<Node>      children;       // internal nodes.  

    public Node(int uniqueID)       
    {
        this.parent     =   null;
        this.label      =   uniqueID;
        this.children   =   new ArrayList<Node>();
        this.leaves     =   new ArrayList<Integer>();
    }
    public void add_leafnode(int data)
    {
        leaves.add(data);
    }
    public void add_internalnode(Node ChildNode)
    {
        children.add(ChildNode);
    }
    // print all leaves, print all children node identifier methods.
    public void print_all_leaves()
    {
        Iterator iter = leaves.iterator();
        while( iter.hasNext() )
        {
            Integer element = (Integer)iter.next();
            System.out.println(element);
        }
    }
    public List<Node> Get_children()
    {
        return children;
    }
}

---

package     mytree;
import      java.util.*;
// Postings.java
class Postings
{
    private     int             parentID;
    private     List<Node>      siblings;       // internal nodes.
    public Postings(int parentID, List<Node> siblings)
    {
        this.parentID   =   parentID;
        this.siblings   =   siblings;
    }
    public void print()
    {
        System.out.println(parentID);
        Iterator iter = siblings.iterator();
        while( iter.hasNext() )
        {
            Integer element = (Integer)iter.next();
            System.out.println(element);
        }
    }
}

---

package     mytree;
import      java.util.*;
// InvertedFile.java
class InvertedFile
{
    private HashMap IF;
    public InvertedFile()
    {
        IF  =   new HashMap();
    }
    public void Add_Posting(int InvertedList, Postings posting)
    {
        IF.put(InvertedList, posting);
    }
}

问题是Java编译器不知道Node.java实际上在~/Desktop/implementation/mytree中的位置。它向我报告的编译错误没有提供任何帮助。

Tracking:mytree tracking$ pwd
/Users/tracking/Desktop/implementation/mytree
Tracking:mytree tracking$ javac Node.java 
Tracking:mytree tracking$ javac Postings.java 
Postings.java:7: cannot find symbol
symbol  : class Node
location: class mytree.Postings
    private     List<Node>      siblings;       // internal nodes.
                     ^
Postings.java:9: cannot find symbol
symbol  : class Node
location: class mytree.Postings
    public Postings(int parentID, List<Node> siblings)
                                       ^
2 errors

另外，我尝试使用javac -d . Postings.java。我总是遇到相同的错误。谁能帮我解决这个问题？预先感谢您。

Answer 1

Java希望在名为mytree的目录中找到源文件。从路径/Users/tracking/Desktop/implementation

编译源

javac mytree/*.java 

Answer 2

从/用户/跟踪/桌面/实现以下命令

javac -cp . Postings.java

node.class应该在与软件包匹配的子目录中。